Re: [KVM PATCH v4 2/2] kvm: add support for irqfd via eventfd-notification interface

[Avi Kivity <avi@redhat.com>]

Gregory Haskins wrote:
> KVM provides a complete virtual system environment for guests, including
> support for injecting interrupts modeled after the real exception/interrupt
> facilities present on the native platform (such as the IDT on x86).
> Virtual interrupts can come from a variety of sources (emulated devices,
> pass-through devices, etc) but all must be injected to the guest via
> the KVM infrastructure.  This patch adds a new mechanism to inject a specific
> interrupt to a guest using a decoupled eventfd mechnanism:  Any legal signal
> on the irqfd (using eventfd semantics from either userspace or kernel) will
> translate into an injected interrupt in the guest at the next available
> interrupt window.
>
>  
> +struct kvm_irqfd {
> +	__u32 gsi;
> +	__u32 flags;
> +};
> +
>   

Please add some reserved space here.

> +int
> +kvm_irqfd(struct kvm *kvm, int gsi, int flags)
> +{
> +	struct _irqfd *irqfd;
> +	struct file *file = NULL;
> +	int fd = -1;
> +	int ret;
> +
> +	irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
> +	if (!irqfd)
> +		return -ENOMEM;
> +
> +	irqfd->kvm = kvm;
>   

You need to increase the refcount on struct kvm here.  Otherwise evil 
userspace will create an irqfd, close the vm and vcpu fds, and inject an 
interrupt.

Otherwise, looks good.

-- 
error compiling committee.c: too many arguments to function